3. Whip remaining 1 cup heavy cream with an electric mixer until soft peaks form. Fold half of the whipped cream into the chocolate mixture to lighten it. Gently fold in remaining whipped cream. For a slightly crunchy mousse, fold in 1 to 2 tablespoons of grated chocolate or cocoa nibs with the second half of the whipped cream.

4. Spoon or pipe mixture into 4 wine glasses or a 1-quart soufflé dish. Cover and refrigerate for 2 hours until set.